⇝ Vitamin D is one of the fat-soluble vitamins, and its role is as a steroid hormone in the body.

⇝ There are two types of vitamin D in food; Vitamin D2 or ergocalciferol in some types of mushroom, vitamin D3 or cholecalciferol in oily fish, fish liver oil and egg yolk is more likely to raise blood vitamin D levels twice as high as vitamin D2.

Difference between Vitamin D2 and D3

Vitamin D in the body is transformed into an active form for use and is considered to be the form formed in the human body when the skin is exposed to sunlight, first described in 1936 and included in the who list of essential medicines. Both vitamin D2 and vitamin D3 are taken, transforming the liver and the kidneys into the active form of vitamin D, known as calcitriol, and when transformed into an active form, they run through several reactions and bind to certain proteins (The vitamin D receptor (VDR) is a nuclear, ligand-dependent transcription factor that in complex with hormonally active vitamin D, 1,25(OH)2D3, regulates the expression of more than 900 genes involved in a wide array of physiological functions)
The difference is that vitamin D3 tends to be more effective than vitamin D2; This means that vitamin D3 supplements are more potent and require fewer doses to achieve the same health benefits than vitamin D2. Vitamin D effectiveness is longer than that of other types of vitamin D, and it should be noted that vitamin D is obtained from foods sourced from animals only

Vitamin D sources:

⇒Meat and meat products:

↠Canned tuna 

Many people would rather eat canned tuna than fresh fish; Because of its unique flavour, easy storage, inexpensive and the fact that tuna is a good source of both vitamin k and vitamin b3, but it also has good vitamin D, since every 100 grams of canned tuna contains 268 IU of vitamin D.

↠Red Salmon:; 

Red salmon is a vitamin D-rich source, as about 85 grams of salmon contains approximately 447 IU of vitamin D and is a good source of protein and omega-3.

↠Egg yolk:

The large egg, weighing about 50 grams, contains 50 IU of vitamin D3 and contains good calcium in its yolk, so the ingestion of eggs into the diet increases daily intake of vitamin D.

↠Beef liver:

Beef liver provides large amounts of protein, essential amino acids, minerals, and vitamins such as vitamin D, providing approximately 42 IU of vitamin D per approximately 85 grams, and one of the main characteristics of this type of meat is that it is soft compared to other meals.

↠Pisces liver oil:

The oil from the Atlantic cod liver, usually in a dietary supplement, contains several nutrients, and is one of the richest sources of vitamin D available; A tablespoon of this oil contains approximately 1360 IU of vitamin D, equivalent to 340% of the daily recommended amount.

⇒Milk and milk products:

Milk and some of its derivatives, such as milk and ricotta cheese, are rich sources of vitamin D and calcium. It should be noted that cheeses generally contain not much vitamin D, but ricotta cheese has the highest amount of this compared to other unsubsidized cheeses
Where this vitamin is five times higher than other cheeses and it should be noted that moderation is recommended for the consumption of milk products as part of the diet; Because they're fat-rich too, so they don't cause unnecessary weight gain.

⇒Plant sources:

Mushrooms are the only vegetarian source of vitamin D, while the amount of vitamin D found in mushrooms varies according to its type.

Is vitamin d found in fruits and vegetables?

vitamin D is not found in fruits, and in fact, vitamin D is not found in plant sources, except for mushrooms and subsidized foods, which are mentioned earlier in the article.

Other sources of Vitamin D

⇒Dietary supplements:

vitamin D is available in other, non-food sources, where vitamin D supplements are found as a dietary supplement, which may be alone or added to other nutrient supplements, such as calcium supplements, and although vitamin D supplements are generally safe; But the poster instructions have to be followed and kept out of reach of the children.

⇒Vitamin D and the sun:

Vitamin D is made in the body when the skin is exposed to sunlight and the amount of vitamin D manufactured depends on several factors, including: 

• Time of day: The sun's rays are stronger between ten in the morning and three in the evening 

• The presence of factors that block sunlight, such as clouds and air pollution. 

• Place of residence: The areas near the equator are exposed to high levels of UV radiation. 

• Melanin content in the skin: a dark brown/black pigment that gives dark skin, eyes and hair, and it should be noted that the higher the melanin content of the skin, the greater the need for sun exposure to obtain sufficient vitamin D.

Recommended vitamin D dosage

The food and nutrition board of the United States has issued authorized and recommended food quantities concerning dietary intake of vitamin D in micrograms

Infants 0 to 12 months  ⟶ 400
Children 1-13 years old  ⟶ 600
People from 14 to 70 years old  ⟶ 600
People 70 and older ⟶ 800
Pregnant and breastfeeding  ⟶ 600

Recommended dose of vitamin d daily:

Infants ⟶ 1000 ~ 1500
Children 1-8 years old ⟶ 2500 ~ 3000
People from 9 years and over ⟶ 4000
Pregnant and breastfeeding women ⟶ 4000

Vitamin D side effect (vitamin D overload): 

Vitamin D poisoning - or so-called vitamin D overload - is considered; a rare case, but it can be serious when vitamin D accumulates in significant amounts in the body, usually as a result of dietary supplementation of vitamin D, not because of dietary intake or exposure to sunlight.
This is because the body can regulate amounts of vitamin D manufactured by sunlight, and subsidized foods do not contain significant amounts of vitamin D, and one of the main complications that can occur in vitamin D poisoning
Hypercalcemia, which can cause several symptoms as:
Nausea, vomiting, weakness, and frequent urination. Symptoms may also develop into bone pain and some kidney problems, such as calcium stones in the kidneys. 

Benefits of Vitamin D:

⇒Promoting bone health:

 Vitamin D plays a role in regulating calcium and maintaining phosphorus levels, which are essential and important metals for bone health. Vitamin D is needed to absorb calcium, thereby reducing levels of vitamin D that can cause rickets in children and osteoporosis in adults.

⇒Reducing the risk of influenza:

 Vitamin D has a good role in fighting flu during the winter. One scientific study found that having 1,200 IU of vitamin D daily in winter reduces the risk of influenza by almost 40%.

⇒Diabetic protection:

 Many different scientific studies have pointed to the relationship between vitamin D and type ii diabetes. This means that obtaining and maintaining appropriate levels of vitamin D will protect you and reduce your risk of diabetes. In contrast, low vitamin D levels in diabetics can adversely affect the excretion of insulin and glucose tolerance.

⇒Keeping babies healthy:

 Infants need to receive appropriate levels of vitamin D to protect them from asthma, eczema, and many different infections.

⇒For a healthy pregnancy:

 Low vitamin D levels in pregnant women increase the risk of pre-eclampsia and caesarean delivery and gestational diabetes. It is also necessary to ensure that vitamin levels do not exceed the required limit for pregnant women, which could also pose a risk to pregnancy health.

⇒Reduce the risk of cancer:

 Vitamin D is important in regulating body cell growth and communication, meaning that appropriate levels of vitamin D have an impact on reducing the risk of cancer.

Lack of Vitamin D ( deficiency ):

Vitamin D deficiency is usually caused by inadequate sun exposure and is common worldwide, leading to reduced calcium and phosphate absorption, which can cause rickets in children or osteoporosis in adults.
Vitamin D deficiency symptoms include:
weakness, muscle and bone pain, and acute vitamin D deficiency in infants can cause muscle spasms or tetany, the first indicator of rickets. Vitamin D deficiency in pregnant women is one of the causes of childhood cramps.

Does vitamin D help lower cholesterol levels

Studies on the relationship between cholesterol and vitamin D showed different results. To date, there was insufficient evidence to determine the relationship. The results of studies on the subject varied considerably.